[Des] is restrained and it is quality. ... The main draw here is Tennant's hypnotic presence. To make a character simultaneously dull and mesmerising takes quite some talent.

Based on Tennant’s performance alone, Des is a compelling watch. But Mays and Watkins put in solid performances, as well.

Tennant gives an unforgettable performance as Nilsen, a portrayal that dances dangerously along the edge of comedy. ... “Des,” created by Luke Neal and Lewis Arnold and directed by Mr. Arnold, is delivered in three tautly constructed, economical episodes about crime and punishment, the crime, as usual, being more engrossing than the punishment.

Des is made to last. It has a confident script directed with a good sense of time and place.

Rare it is to watch a drama about a serial killer that leaves you feeling as though the victims have been done a service. In the end, perhaps the greatest accolade that can be given this sensitive, finely worked piece is that Nilsen himself, attention-seeking narcissist though he was, would surely have hated it.

In its determination not to be sensationalistic errs on the side of vagueness. (If the point is that Nilsen was just an empty shell, it’s not made in a way that I found very compelling or particularly chilling.) ... Enjoying “Des” — well, appreciating “Des” — has to do with its details, which include the seamless, highly capable ensemble work among Mays, Watkins, Tennant and Barry Ward (as Jay’s right-hand man) and the appropriately musty evocation of the period by the production designer Anna Higginson and the cinematographer Mark Wolf.

The result is a moderately engaging entry in the ever-expanding serial-killer thriller subgenre, notable primarily for its unique post-capture investigative angle and Tennant’s superb portrayal of a madman with a bottomless capacity for depravity.

It's worth watching this for David Tennant and Daniel Mays, who are both eminently watchable. However, considering it's a story about a serial killer it's a pretty dry affair. There's a lot more to the Dennis Neilsen story but we just get the end of it.